1. Field of the Invention
The present invention relates to ruthenium(II)-BINAP complexes and, more particularly, relates to ruthenium(II)-BINAP diketonate complexes. The subject Ru(II)-BINAP complexes are particularly suitable as asymmetric hydrogenation catalysts.
2. Related Art
Ruthenium(II)-BINAP complexes with ClO.sub.4, BF.sub.4, PF.sub.6, triethylamine and diacetate ([OAc].sub.2) are known. See, for example, U.S. Pat. Nos. 4,766,225; 4,691,037; and EP272,787. However, the synthesis of such complexes is extremely tedious and expensive and produces a mixture of complex species along with impurities which are difficult to remove. For example, Ru(BINAP)(OAc).sub.2 is produced from [Ru(II)(COD)Cl.sub.2 ].sub.n, (wherein COD represents cyclooctadiene) which is much more expensive than Ru(III) species such as RuCl.sub.3. In addition, the product yields are quite low (50-68%). See Inorgan. Chem., 1988, 27, 566-569.